Computerized mapping systems have been developed to search for, identify, and discover information about geographic locations. One form of such computerized mapping systems includes travel-planning Internet websites. With an excess of 50 million unique monthly users, such map sites are a very popular offering. Examples of such sites include AOL's MapQuest, Yahoo's Telcontar-based maps, and Microsoft's MapPoint.net suite. Such sites all work along the lines of a common model, as will now be described.
When a web user asks for a new map view (e.g., by entering a postal address, or by clicking a navigation link next to a current map view), the user's web browser sends to a web server a request indicating the boundaries of the new map view. The web server in turn extracts the corresponding vector-based map data from a database, and draws a bitmap image of the map. The server then converts the bitmap to an image format supported by the user's web browser and returns the image, sometimes embedded in HTML, to the user's web browser so that it can be displayed. Other map websites, such as Britain's MultiMaps or Australia's WhereIs utilize a raster-based map database instead. In these cases, it is not necessary to extract vectors and draw a map image. Rather, these functions are replaced by simply extracting the appropriate part of a larger, pre-rendered image.
Whether vector-based or raster-based, such existing map systems typically provide a single view of map information. Thus, when a user is zoomed on a particular map area, areas outside that zoomed area cannot be scene or otherwise referenced by the user. In such a case, the user may need to pan in a certain direction to view a new map area. However, if the user does not know which direction to pan, then the user will have to zoom out first, until the desired map area is in view, and then zoom back on that desired area. In this sense, a single view map limits the amount of flexibility available to the user.
What is needed, therefore, are digital mapping techniques that provide more flexibility to the user through the use of multiple views of map information